Sprinkler heads with rotatable pop-up nozzles propelled by water pressure are presently in widespread use. These heads are capable of discharging relatively large volumes of water over large areas. Many types of self-propelled rotatable sprinkler heads are known to the art. One particular type of such irrigation sprinkler heads, for example, is described in U.S. Pat. No. 4,650,118 which is assigned to the present Assignee. The sprinkler head described in the patent includes a pop-up assembly which is caused to extend up through the cap of the housing against internal spring force by internal water pressure, and in which the extended pop-up assembly is driven by a water-powered motor. A nozzle mounted on the upper end of the pop-up assembly is turned back and forth through a preset arc in order to irrigate a sector of land of a particular size.
The sprinkler described in U.S. Pat. No. 4,650,118 is constructed so that when the pop-up assembly is turned to a particular angular position, a trip tab on the pop-up assembly engages a shifter, and it moves the shifter a small angular increment which in turn engages a pawl and causes the mechanism to reverse so that the pop-up assembly is rotated in the opposite direction to the other end of its preset arc, at which the procedure is repeated by a second trip tab.
The sprinkler head to be described in the present application is of the same general type as the sprinkler head of U.S. Pat. No. 4,650,118. However, it will become evident as the description proceeds that the present invention is not limited to that particular sprinkler head.
An objective of the present invention is to provide a clutch mechanism in the sprinkler head to protect the internal components of the sprinkler in the presence of forced rotation of the pop-up assembly by vandals or others.
Another object of the invention is to provide such a clutch mechanism which, upon operation, does not disturb in any way the previously preset trigger mechanism of the sprinkler head.